ユーザーコントロール内のデータリストでnull参照が返される

Question

aspxページのDatalistコントロールをusercontrolに移動し、aspxページを参照しました。このプロセスでは、データリスト（ItemDataBoundメソッドとDisplayメソッド）のソースコードも移動しました。私は、Datalistの母集団のソースとして「Datatable」を使用しています。コントロールをユーザーコントロールに移動した後、データテーブルをソースとしてdatalistに割り当てようとすると、NullReferenceがスローされます。ここ

public partial class Controls_ProductSpecifications : System.Web.UI.UserControl 
{ 
    protected void Page_Load(object sender, EventArgs e) 
    { 
     //no code yet here... 
    } 

    public void DisplaySpecifications(SearchResultItem sri,bool IsMobilePage) 
    { 
     List<Category> breadcrumbCategories = sri.BreadcrumbCategories; 
     Category templateCat = breadcrumbCategories[breadcrumbCategories.Count - 1]; 

     ParametricColumnSortOrder customDimSortOrder = null; 
     int rowPosition = 0; // manufacturer, product category, rohs 
     bool isUnclassified = false; 

     // -- get the sorted parametric list from database 
     if (templateCat.Id.ToString() != null) 
      customDimSortOrder = new ParametricColumnSortOrder(Convert.ToInt64(templateCat.Id), false, true); 

     //List<ParametricAttributeGroup> plist = sri.ParametricDimensions; 
     if (breadcrumbCategories[0].Name == "Unclassified") 
     { 
      ////if (breadcrumbCategories.Count > 1) 
      ////{ 
      //// //---{ Create an unclassifed attribute group } 
      //// ParametricAttributeGroup pag = new ParametricAttributeGroup(breadcrumbCategories[0].Id, breadcrumbCategories[0].Name); 
      //// pag.ParametricAttributes.Add(new ParametricAttribute(breadcrumbCategories[1].Id, breadcrumbCategories[1].Name)); 
      //// plist.Add(pag); 
      ////} 
     } 

     var dt = new DataTable(); 
     dt.Columns.Add("Dimension"); 
     dt.Columns.Add("DimensionID"); 
     dt.Columns.Add("Attribute"); 
     dt.Columns.Add("AttributeID"); 
     dt.Columns.Add("CheckBox"); 
     dt.Columns.Add("CheckBoxState"); 

     DataRow dr; 

     List<ParametricAttributeGroup> translatedAttGrp = sri.ParametricDimensions; 

     LanguageDataAccess.GetTranslatedAttributes(translatedAttGrp, Language.CurrentLanguageCulture); 

     foreach (ParametricAttributeGroup attributeGroup in translatedAttGrp) 
     { 
      ParametricAttribute attribute = attributeGroup.ParametricAttributes[0]; 

      dr = dt.NewRow(); 
      dr["Dimension"] = attributeGroup.Name; 
      dr["DimensionID"] = attributeGroup.Id; 
      dr["Attribute"] = attribute.Value; 
      dr["AttributeID"] = attribute.Id; 
      dr["CheckBox"] = "false"; 

      string grpname = attributeGroup.Name; 
      // -- get the original name instead of the translated name for comparision -- 
      if (attributeGroup is LocalizationParametricAttributeGroup) 
      { 
       grpname = ((LocalizationParametricAttributeGroup)attributeGroup).OriginalName; 
      } 

      if (grpname == "Manufacturer") 
      { 
       dr["Dimension"] = Resources.lblManufacturer; 
       dr["CheckBoxState"] = "0"; 
       dt.Rows.InsertAt(dr, rowPosition); 
       rowPosition++; 
      } 
      else if (grpname == "Product Category") 
      { 
       // -- don't show product category if this product is under Unclassified -- 

       isUnclassified = breadcrumbCategories.Any(cat => cat.Name == Resources.MyMouser.lblUnclassified); 

       if (!isUnclassified) 
       { 
        dr["Dimension"] = attributeGroup.Name; 
        dr["Attribute"] = templateCat.Name; 
        dr["AttributeID"] = templateCat.Id; 
        dr["CheckBoxState"] = "0"; 
        dt.Rows.InsertAt(dr, rowPosition); 
        rowPosition++; 
       } 
      } 
      else if (grpname == "Unclassified") 
      { 
       dr["Dimension"] = Resources.lblUnclassified; 
       dr["CheckBoxState"] = "0"; 
       dt.Rows.InsertAt(dr, rowPosition); 
       rowPosition++; 
      } 
      else if (grpname == "RoHS - Mouser") 
      { 
       dr["Dimension"] = Resources.MyMouser.litHeaderRoHS; 
       dr["Attribute"] = SearchHelper.CreateRoHSLabel(sri,sri.EnRoHSStatus, isUnclassified,IsMobilePage); 
       dt.Rows.InsertAt(dr, rowPosition); 
       rowPosition++; 
      } 
      else if (grpname == "Standard Pack Qty") 
      { 
       dr["Dimension"] = Resources.MyMouser.lblfactrPakcQty; 
       dt.Rows.Add(dr); 
      } 
      else 
      { 
       dt.Rows.Add(dr); 
      } 
     } 

     // -- sort the visiable fields -- 
     if (customDimSortOrder != null) 
     { 
      for (int dimSortIndex = 0; dimSortIndex < customDimSortOrder.Count; dimSortIndex++) 
      { 
       foreach (DataRow oldRow in dt.Rows) 
       { 
        if (customDimSortOrder.AllKeys[dimSortIndex] == oldRow["DimensionID"].ToString()) 
        { 
         dr = dt.NewRow(); 
         dr["Dimension"] = oldRow["Dimension"]; 
         dr["DimensionID"] = oldRow["DimensionID"]; 
         dr["Attribute"] = oldRow["Attribute"]; 
         dr["AttributeID"] = oldRow["AttributeID"]; 
         dr["CheckBoxState"] = "0"; 
         dt.Rows.Remove(oldRow); 
         dt.Rows.InsertAt(dr, rowPosition); 
         rowPosition++; 
         break; 
        } 
       } 
      } 
     } 

     //aliases information - shawn weng 
     if (sri.Aliases != "") 
     { 
      dr = dt.NewRow(); 
      dr["Dimension"] = Resources.MyMouser.lblpartaliases; 
      dr["DimensionID"] = 0; 
      dr["Attribute"] = sri.Aliases; 
      dr["AttributeID"] = 0; 
      dr["CheckBox"] = "false"; 
      dt.Rows.Add(dr); 
     } 
     try 
     { 
      DataList dl1 = (DataList) this.FindControl("dlspec"); 
      dl1.DataSource = dt; 
      dl1.DataBind(); 
     } 
     catch (Exception ex) 
     { 
      throw; 
     } 

    } 

    protected void dlspec_ItemDataBound(object sender, DataListItemEventArgs e) 
    { 
     if ((e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) 
      && e.Item.DataItem != null) 
     { 
      // -- checkbox -- 
      var ck = e.Item.FindControl("FindSimilarCheckbox") as CheckBox; 
      if (ck != null) 
      { 
       ck.ID = ck.Text; 
       ck.Text = ""; 

       var lbldim = e.Item.FindControl("lblDimension") as Label; 
       if (lbldim != null) 
       { 
        if (lbldim.Text.Contains(Resources.MyMouser.lblManufacturer) || lbldim.Text.Contains(Resources.MyMouser.lblProductCategory)) 
        { 
         ck.Checked = true; 
        } 
        if (lbldim.Text.Contains(Resources.MyMouser.lblfactrPakcQty)) 
        { 

         string PackageQtylnk = "<a href=JAVASCRIPT:OpenFactoryQty();>" + Resources.MyMouser.lblfactrPakcQty + "</a>"; 
         lbldim.Text = string.Format(PackageQtylnk); 
         lbldim.CssClass = "factorypackage"; 
        } 
       } 
      } 
     } 
    } 
} 

はascxファイルのページのマークアップです：

<%@ Control Language="C#" AutoEventWireup="true"  CodeBehind="ProductSpecifications.ascx.cs" Inherits="MouserWeb.Controls.Controls_ProductSpecifications" %> 
<asp:DataList ID="dlspec" runat="server" GridLines="Vertical" OnItemDataBound="dlspec_ItemDataBound"> 
<FooterStyle BackColor="#CCCCCC" /> 
<AlternatingItemStyle CssClass="alt-grey" /> 
<SelectedItemStyle BackColor="#000099" Font-Bold="True" ForeColor="White" /> 
<HeaderStyle BackColor="Black" Font-Bold="True" ForeColor="White" /> 
<ItemTemplate> 
    <table width="550px"> 
    <tr> 
     <td class="leftcol"> 
     <asp:Label ID="lblDimension" runat="server" Text='<%# Eval("Dimension") %>'></asp:Label>: 
     </td> 
     <td class="ProductDetailData"> 
     <asp:Label ID="lblName" runat="server" Text='<%# Eval("Attribute") %>'></asp:Label> 
     </td> 
     <td class="find-similar"> 
     <asp:CheckBox ID="FindSimilarCheckbox" runat="server" Checked='<%# Eval("CheckBox")=="true"? true:false %>' 
      Text='<%# Eval("AttributeID") %>' Visible='<%# Eval("CheckBoxState")=="0"? true:false %>' /> 
     <%--<input name='<%# Eval("DimensionID") %>' id='<%# Eval("DimensionID") %>' type="checkbox" checked='<%# Eval("CheckBox")=="true"? true:false %>' />--%> 
     </td> 
    </tr> 
    </table> 
</ItemTemplate> 
</asp:DataList> 

は何が間違っているように見えるん？これについてもっと情報（コード）を提供できるかどうか教えてください...あなたの貴重なお手伝いをお寄せいただきありがとうございます。

Answer 1

DisplaySpecifications(...)に電話をしても表示されません。DataListをバインドしますか？

protected void Page_Load(object sender, EventArgs e) 
{ 
    //no code yet here... 
    if(!Page.IsPostBack) 
    { 
     DisplaySpecifications(...); 
    } 
}